A teacher is designing a program to process pseudocode projects written by her students. Each student project is stored in a text file. The process is split into a number of stages. Each stage performs a different task and creates a new file named as shown: File name Comment MichaelAday_src.txt student project file produced by student Michael Aday MichaelAday_S1.txt file produced by stage 1 MichaelAday_S2.txt file produced by stage 2 The teacher has defined the first program module as follows: Module Description DeleteComment() • called with a parameter of type string representing a line of pseudocode from a student's project file • returns the line after removing any comments Note on comments: A comment starts with two forward slash characters and includes all the remaining characters on the line. The following example shows a string before and after the comment has been removed: Before: IF X2 > 13 THEN //check if limit exceeded After: IF X2 > 13 THEN

Mark scheme

Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.

1. [8] FUNCTION DeleteComment(Line : STRING) RETURNS STRING
2. DECLARE NewLine, TwoChars : STRING
3. DECLARE Count, TrimTo : INTEGER
4. CONSTANT Comment = "//"
5. NewLine ← Line
6. TrimTo ← 0
7. Count ← 1
8. WHILE Count < LENGTH(Line) AND TrimTo = 0
9. TwoChars ← MID(Line, Count, 2) // extract 2 chars
10. IF TwoChars = Comment THEN
11. TrimTo ← Count
12. ENDIF
13. Count ← Count + 1
14. ENDWHILE
15. IF TrimTo <> 0 THEN
16. NewLine ← LEFT(Line, TrimTo - 1)
17. ENDIF
18. RETURN NewLine
19. ENDFUNCTION
20. Mark as follows:
21. 1 Loop to length of Line (parameter) // length of Line -1
22. 2 Terminate loop on first double slash
23. 3 Attempt to extract one/two characters in a loop
24. 4 Check for "//" after attempt at extraction in a loop
25. 5 Record start position of comment // Calculate amount of trim required
26. 6 Attempt to trim Line from start of comment
27. 7 Completely correct trimmed Line from start of comment
28. 8 Return Line after a reasonable overall attempt
29. [7] FUNCTION Stage_1(StudentName : STRING) RETURNS INTEGER
30. DECLARE OldFile, NewFile, Line : STRING
31. DECLARE Count : INTEGER
32. OldFile ← StudentName & " src.txt"
33. NewFile ← StudentName & " S1.txt"
34. OPENFILE OldFile FOR READ
35. OPENFILE NewFile FOR WRITE
36. Count ← 0
37. WHILE NOT EOF(OldFile)
38. READFILE OldFile, Line
39. Line ← DeleteComment(Line)
40. IF LENGTH(Line) <> 0 THEN
41. WRITEFILE NewFile, Line
42. Count ← Count + 1
43. ENDIF
44. ENDWHILE
45. CLOSEFILE OldFile
46. CLOSEFILE NewFile
47. RETURN Count
48. ENDFUNCTION
49. Mark as follows:
50. 1 Generate filenames condone missing "_"
51. 2 Open both files in correct modes and subsequently close
52. 3 Loop to EOF(OldFile)
53. 4 Read a line from OldFile and execute DeleteComment() in a loop
54. 5 Skip blank lines after DeleteComment() in a loop
55. 6 Write Line to stage 1 file and increment Count
56. 7 Return the number of lines after a reasonable attempt at counting